1. Field of the Invention
This invention relates to an apparatus for detecting the position of an object which undergoes rectilinear motion, such as the imaging lens of a camera.
2. Description of the Related Art
In order to adjust the focal point automatically in an AF (automatic focusing) camera, it is necessary for the imaging lens of the camera to be moved to any position. The same is true for the zoom lens in a camera possessing a zoom function. The drive system for moving the lens is constituted by a motor, a speed reduction mechanism which includes gears, a mechanism for converting the rotational motion of the motor into rectilinear motion and so on. However, an unavoidable problem is the fact that some error in lens position develops from the inertia possessed by these mechanisms, their precision, which includes play, and external forces acting upon the mechanisms. This error accumulates with repeated forward rotation, stopping and reverse rotation of the motor.